1. Field of Invention
The present invention relates, in general, to a tubular back beam assembly for a vehicle and a method of manufacturing the same, and, more particularly, to a tubular back beam assembly for a vehicle, in which a plurality of tubular back beams are coupled in a vertically stacked structure in a surface contact fashion, and a method of manufacturing the same.
2. Description of Related Art
To protect a vehicle body and a passenger in the event of a collision, a back beam assembly is mounted in the front and rear of the vehicle.
FIG. 1 illustrates an example of a tubular back beam assembly. A conventional tubular back beam assembly 1 has a structure in which an upper beam 1a and a lower beam 1b which have a circular cross section are installed at an interval in a vertical direction, intermediate portions of the upper beam 1a and the lower beam 1b are coupled using a coupling bracket 1c, and stays 3 or crash boxes used to couple to side members 2 are coupled to both ends of the upper beam 1a and the lower beam 1b. 
The tubular back beam assembly 1 configured as described above has the effect reducing weight and cost compared to a general integrated back beam. In particular, each of the upper beam 1a and the lower beam 1b can dissipate and absorb collision energy. Thereby, there is an advantage in that collision performance can be more effectively satisfied.
However, the conventional tubular back beam assembly 1 as described above has a structure in which the upper beam 1a and the lower beam 1b are separated from each other, and the upper beam 1a and the lower beam 1b which are separated from each other are coupled by the coupling bracket 1c. Thus, in the conventional tubular back beam assembly 1, coupling strength of the upper beam 1a and the lower beam 1b is insufficient. There is a high probability of the upper beam 1a and the lower beam 1b being vertically widened by collision energy in the event of the collision of the vehicle. In this case, the conventional tubular back beam assembly 1 cannot effectively cope with the collision. Thus, the vehicle body suffers heavy damage, and the passenger may be greatly injured.
In addition, the upper beam 1a and the lower beam 1b of the conventional tubular back beam assembly 1 are manufactured by pressing or extruding a general steel pipe. The upper beam 1a and the lower beam 1b manufactured as described above have a disadvantage in that they are heavy due to a thick construction and, in particular, it is difficult to satisfy sufficient collision performance due to weak strength.
The information disclosed in this Background section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.